The priming of metal parts, especially automobile bodies, is carried out nowadays largely by an electrodeposition method, predominantly in the form of a cationic electrodeposition (CED). In this method the substrate is immersed in an aqueous CED bath and connected as the cathode. By applying direct current the binder is then deposited from the bath onto the substrate. The deposited binder is then cured by storing or other methods. Suitable binders for such CED baths are in particular those containing amino groups. Using acid, these amino groups are converted to ammonium salts and the binders then become soluble or dispersible in water. However, especially when producing relatively thick coats on galvanized substrates, defects often occur in the stoved film. It is the object of the present invention to avoid or to reduce these defects.